A Generating Function applied on a reaction model for the selective separation of Pb(II) and Hg(II) via HFSLM

• HFSLM can successfully treat Pb(II) and Hg(II) achieving less than the regulatory discharge.
• The model was developed to describe the transport of Pb(II) and Hg(II) in both feed and stripping sides.
• The model was solved by the concept of Generating Function.
• Pb(II) and Hg(II) concentrations obtained from the model agreed with the experimental results.

The separation of Pb(II) and Hg(II) via a hollow fiber supported liquid membrane (HFSLM) is presented. The experiment studied the influence of types of extractants, the concentration of selected extractants, setting modules, operating time together with flow rates of feed and stripping solutions. The mathematical model used to predict the concentration of Pb(II) and Hg(II) in both feed and stripping solutions was developed based on chemical reactions. The results clearly showed that a double-module HFSLM can selectively separate Pb(II) and Hg(II) at a very low concentration. Optimum condition was achieved using 0.03 M D2EHPA and 0.06 M Aliquat 336 as the extractant for first and second modules. The flow rates of the feed and stripping solutions were 100 mL/min. The complicated series of differential equations arising from the model was solved using the concept of Generating Function. The concentration of Pb(II) and Hg(II) in feed and stripping solutions, obtained from the model, fitted well with that from the experimental results as shown in Fig. 10. This indicated that the extraction and stripping reactions were important factors that governed the rate of Pb(II) and Hg(II) transport across the liquid membrane phase.

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